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Abstract:

A method of recycling ruthenium (Ru) and Ru-based alloys comprises steps
of: providing a solid body of Ru or a Ru-based alloy; segmenting the body
to form a particulate material; removing contaminants, including Fe, from
the particulate material; reducing the sizes of the particulate material
to form a powder material; removing contaminants, including Fe, from the
powder material; reducing oxygen content of the powder material to below
a predetermined level to form a purified powder material; and removing
particles greater than a predetermined size from the purified powder
material. The purified powder material may be utilized for forming
deposition sources, e.g., sputtering targets.

Claims:

1. A method of recycling ruthenium (Ru) and Ru-based alloys, comprising
steps of:(a) providing a solid body of Ru or a Ru-based alloy;(b)
segmenting said solid body to form a particulate material;(c) removing
contaminants, including iron (Fe), from said particulate material;(d)
reducing the particle sizes of said particulate material to form a powder
material;(e) removing contaminants, including Fe, from said powder
material;(f) reducing oxygen content of said powder material to below a
predetermined level to form a purified powder material; and(g) removing
particles greater than a predetermined size from said purified powder
material.

2. The method according to claim 1, wherein:step (a) comprises providing a
solid body in the form of a spent deposition source.

19. A recycled Ru or Ru-based alloy made by the process according to claim
18, in the form of a powder material having a 325 mesh size and tap
density >˜5 gm/cm.sup.3.

20. A Ru deposition source fabricated from the Ru powder material of claim
19, with density comparable to that of a Ru deposition source fabricated
from virgin Ru powder material and hardness greater than that of a Ru
deposition source fabricated from virgin Ru powder material.

21. The deposition source as in claim 20, in the form of a sputtering
target.

22. A RuCr alloy deposition source fabricated from the RuCr powder
material of claim 19, with density comparable to that of a RuCr
deposition source fabricated from virgin RuCr powder material and
hardness greater than that of a RuCr deposition source fabricated from
virgin Ru powder material.

23. The deposition source as in claim 22, in the form of a sputtering
target.

Description:

FIELD OF THE DISCLOSURE

[0001]The present disclosure generally relates to methodology for
recycling ruthenium (Ru) and Ru-based alloy materials and to products
made from the recycled Ru and Ru-based alloy materials. The disclosure
has particular utility in recycling of Ru and Ru-based alloy deposition
targets, e.g., sputtering targets, and to targets made from powders of
the recycled Ru and Ru-based alloy materials.

BACKGROUND OF THE DISCLOSURE

[0002]Ruthenium and ruthenium-based alloy materials are increasingly
utilized in the manufacture of a number of advanced technology products,
e.g., as coupling layers in high performance, high areal recording
density anti-ferromagnetically coupled ("AFC") magnetic recording media
and as adhesion/seed layers in copper-based "back-end" metallization
systems of high integration density semiconductor integrated circuit
("IC") devices. Such layers are typically formed by sputter deposition
processing, e.g., magnetron sputtering, utilizing Ru or Ru-based alloy
targets. However, use of the sputtering targets in a given application is
limited due to consumption of the target over time, primarily because of
concern of target penetration due to irregular or uneven (i.e., local)
sputtering over the target surface. Economic considerations arising from
the high cost of Ru and Ru-based alloys dictate recovery of these
materials from spent targets.

[0008]In view of the foregoing, there exists a clear need for improved,
more cost effective methodology for recycling Ru and Ru-based alloy
materials for facilitating re-use thereof, e.g., as in the manufacture of
Ru and Ru-based deposition targets (such as sputtering targets) using
recycled materials.

[0013]Additional advantages and features of the present disclosure will be
set forth in the disclosure which follows and in part will become
apparent to those having ordinary skill in the art upon examination of
the following or may be learned from the practice of the present
disclosure. The advantages may be realized and obtained as particularly
pointed out in the appended claims.

[0014]According to an aspect of the present disclosure, the foregoing and
other advantages are achieved in part by an improved method of recycling
ruthenium (Ru) and Ru-based alloys, comprising steps of:

[0015](a) providing a solid body of Ru or a Ru-based alloy;

[0016](b) segmenting the solid body to form a particulate material;

[0017](c) removing contaminants, including iron (Fe), from the particulate
material;

[0018](d) reducing the particle sizes of the particulate material to form
a powder material;

[0019](e) removing contaminants, including Fe, from the powder material;

[0020](f) reducing oxygen content of the powder material to below a
predetermined level to form a purified powder material; and

[0021](g) removing particles greater than a predetermined size from the
purified powder material.

[0022]According to embodiments of the present disclosure, step (a)
comprises providing a solid body in the form of a spent deposition
source, e.g., a sputtering target, and the method further comprises a
step of:

[0025]Further embodiments of the present disclosure include those wherein
step (h) comprises addition of a predetermined amount of at least one
element to the purified powder prior to consolidating, e.g., as when step
(a) comprises providing a solid body of a RuCr alloy; and step (h)
comprises adding a predetermined amount of chromium (Cr) to the purified
powder.

[0026]According to embodiments of the present disclosure, step (b)
comprises optional jaw crushing followed by hammer milling; step (c)
comprises a first leaching to remove iron (Fe) and other contaminants,
followed by drying; step (d) comprises impact milling; step (e) comprises
a second leaching to reduce Fe content to <˜500 ppm and remove
other contaminants, followed by drying, and further comprises performing
a magnetic separation to remove Fe prior to the second leaching; step (f)
comprises reducing oxygen content to <˜500 ppm, as by performing
a reduction process in an atmosphere containing hydrogen gas and
annealing the purified powder material during the reduction process.

[0028]Another aspect of the present disclosure is recycled Ru or Ru-based
alloys made by the above process, e.g., powder materials having a desired
mesh size, e.g., 325 mesh, and tap density >˜5 gm/cm3.

[0029]Still another aspect of the present invention is Ru and Ru
alloy-based deposition sources, e.g., Ru and RuCr sputtering targets,
fabricated from the powder material formed by the above process, with
densities comparable to those of Ru and Ru-based sources/targets
fabricated from virgin Ru and RuCr powder material and hardness greater
than those of Ru and Ru-based sources/targets fabricated from virgin Ru
and RuCr powder material.

[0030]Additional advantages and aspects of the present disclosure will
become readily apparent to those skilled in the art from the following
detailed description, wherein only the preferred embodiments of the
present disclosure are shown and described, simply by way of illustration
of the best mode contemplated for practicing the present disclosure. As
will be realized, the disclosure is capable of other and different
embodiments, and its several details are capable of modification in
various obvious respects, all without departing from the spirit of the
present disclosure. Accordingly, the drawing and description are to be
regarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWING

[0031]The following detailed description of the embodiments of the present
disclosure can best be understood when read in conjunction with the
following drawing, in which:

[0032]FIG. 1 is a flow chart schematically showing an illustrative, but
non-limitative embodiment according to the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0033]The present invention addresses and effectively solves, or at least
mitigates, several problems and/or disadvantages associated with
conventional chemical-based methodology for recycling products/apparatus
containing Ru and Ru-based alloy materials, e.g., thin film deposition
sources such as sputtering targets, and is based upon discovery that
recovery/recycling of Ru and Ru-based alloy materials can be formed in an
efficient, cost-effective manner which substantially reduces the
processing interval.

[0034]More specifically, the presently disclosed methodology overcomes the
following disadvantages associated with conventional chemical refining
processing for Ru recovery/recycling, including the high cost; extremely
long processing intervals, e.g., on the order of about 12 weeks; the
porous and highly agglomerated nature of the recycled product, rendering
it undesirable for use in subsequent fabrication of new deposition
sources, such as sputtering targets; and the relatively low tap density
of the recycled product powder, i.e., about 4.0 gm/cm3 on average,
necessitating increase in the packing density prior to target formation.

[0035]The improved methodology for Ru recovery/recycling will now be
described in detail with reference to FIG. 1, which is a flow chart
schematically showing an illustrative, but non-limitative, embodiment
according to the present disclosure wherein spent sputtering targets are
subjected to a recycling process for recovering high purity Ru and
Ru-based alloy materials for re-use in the manufacture of new sputtering
targets.

[0036]In a first step according to the process methodology, a solid body
of Ru or Ru-based alloy material, i.e., a spent sputtering target is
provided and mechanically segmented into appropriately sized particles,
illustratively 1 mm (˜0.04 in) pieces. Mechanical segmentation may,
if desired, be accomplished via a 2-stage process comprising an initial
jaw crushing step to form pieces in the 30-50 mm (˜1-2 in.) size
range, followed by hammer milling to form smaller pieces in the 1 mm
(˜0.04 in) size range.

[0037]According to the next step of the process methodology, the smaller
pieces are subjected to a first leaching, e.g., with a strong mineral
acid such as hydrochloric (HCl) or nitric (HNO3) acid, at room
temperature for from about 12 to about 48 hrs., in order to remove
contaminants from the pieces, especially any iron (Fe) introduced during
the segmentation process. The leached particles are then subjected to a
first oven drying, and impact milled to form a powder material with about
325 mesh size.

[0038]The powder material is then subjected to a second leaching, e.g.,
with a strong mineral acid such as hydrochloric (HCl) or nitric
(HNO3) acid, at room temperature for from about 12 to about 48 hrs.,
to further remove contaminants, followed by a second oven drying. The Fe
content of the dried powder after the second leaching should be very low,
i.e., <500 ppm, in order to prevent, or at least limit, diffusion of
any Fe present on the surfaces of the powder particles into the interior
thereof during subsequent processing, e.g., hydrogen reduction. In this
regard, it should be recognized that any Fe present in the interior of
the powder particles is difficult to remove, e.g., by leaching.

[0039]According to the next step of the instant process methodology, the
dried powder from the second leaching step is subjected to reduction in a
hydrogen (H2) gas atmosphere at about 1,000° C. for about 12
hrs., to reduce oxygen content of the powder to below a desired level,
typically <500 ppm. An advantageous feature of the present methodology
annealing of the powder during the hydrogen reduction process, whereby
any work hardening of the material incurred during the earlier
segmentation processing is reduced. The feature of annealing during
hydrogen reduction is critical for facilitating subsequent consolidation
of the recycled powder.

[0041]The purified recycled Ru or Ru-based alloy material can be utilized,
inter alia, for making Ru and Ru-based alloy deposition sources, e.g.,
sputtering targets. In the case of recycled RuCr powder, Cr may be added
thereto according to the desired final composition of the deposition
source.

[0042]According to methodology afforded by the instant disclosure, the
recycled purified Ru or Ru-based alloy powder is subjected to
consolidation processing, which may include optional CIP followed by HIP,
vacuum hot pressing, or spark plasma sintering to achieve full density.
In this regard, whereas CIP is required for chemically recycled Ru or
Ru-based alloy powder because of its low tap density (<5 gm/cm3),
CIP of recycled Ru or Ru-based alloy powder formed according to the
present methodology is not necessarily required in view of its higher tap
density (>5 gm./cm3).

[0043]Ru and Ru alloy-based deposition sources, e.g., Ru and RuCr
sputtering targets, fabricated from the powder material formed by the
above process by conventional powder metallurgical techniques, have
densities comparable to those of Ru and Ru-based sources/targets
fabricated from virgin Ru and RuCr powder material and hardness greater
than those of Ru and Ru-based sources/targets fabricated from virgin Ru
and RuCr powder material.

[0046]1. the total recycling time is about 2 weeks, which is only about
17% of the recycling time required by the conventional chemical recycling
process (i.e., about 12 weeks);

[0047]2. recycling cost is significantly less expensive than that of the
conventional chemical recycling process;

[0048]3. the recycled powder is non-porous and not agglomerated, whereas
the recycled powder produced by the conventional chemical recycling
process is porous and highly agglomerated. In this regard, agglomerated
powder is not preferred for use in deposition source (e.g., sputtering
target) manufacture via powder metallurgical techniques; and

[0049]4. The recycled powder produced by the present process has a high
average tap density >˜5 gm/cm3 (as compared with an average
tap density of only about 4 gm/cm3 with powder produced via
conventional chemical recycling), thereby facilitating formation of
deposition sources via powder metallurgical techniques not requiring a
CIP step to increase tap density. As a consequence, the present
methodology affords further cost and processing time reductions.

[0050]In the previous description, numerous specific details are set
forth, such as specific materials, structures, processes, etc., in order
to provide a better understanding of the present invention. However, the
present invention, can be practiced without resorting to the details
specifically set forth herein. In other instances, well-known processing
techniques and structures have not been described in order not to
unnecessarily obscure the present invention.

[0051]Only the preferred embodiments of the present invention and but a
few examples of its versatility are shown and described in the present
disclosure. It is to be understood that the present invention is capable
of use in various other combinations and environments and is susceptible
of changes and/or modifications within the scope of the inventive concept
as expressed herein.